My boyfriend wants me to get off birth control so we can have a baby

My boyfriend and I are both 23 and he told me yesterday he wants a baby. I just got my IUD put in to help with my periods and I don’t want a baby right now . I don’t feel ready. He keeps asking if I will give him a baby and I tell him yes eventually but I don’t feel ready to give up my body plus I’m trying to lose weight 😫 how can I explain it to him